1. Field of the Invention
This invention relates to a device for indicating exposure information in the viewfinder of a camera, and more particularly to a device for indicating various kinds of information in the viewfinder of a photographic camera by use of electrically operated light emitting elements.
2. Description of the Prior Art
In the conventional photographic cameras, it has been known to indicate various kinds of information such as the brightness of the object to be photographed, the shutter speed or diaphragm hole size automatically controlled by exposure controlling means, the condition of the power voltage and so forth in the visual field of the viewfinder so that the photographer can see such information together with the image viewed through the viewfinder. As for the light emitting elements, electric lamps have generally been used. Recently, it has been proposed to use various kinds of solid-state light emitting elements such as light emitting diodes and electro-luminescent materials.
The above described indicating device using solid-state light emitting elements suffers from the defect that the light emitting elements sometimes become hard to see when the brightness level of the image viewed through the viewfinder is much higher than that of the light emitting elements. In order to eliminate such a defect, it has been known to use a separate light measuring circuit in addition to the light measuring circuit connected with a circuit for selectively operating the light emitting elements to control the brightness of the light emitting elements by changing the operating voltage of the elements in accordance with the brightness of the object to be photographed.
The above described means for controlling the brightness of the light emitting elements is disadvantageous in that two light measuring means must be separately provided in the camera. Another disadvantage inherent in the above described indicating device with the brightness controlling means is that, when light emitting diodes as of GaAsP are used, the brightness of the light emitting diodes cannot be changed over a wide range by changing the operating voltage.
Under the above described conventional disposition of the information indicating means in a camera, there is a demand for a device for indicating information in the viewfinder of a camera in which only one light measuring circuit is used and the brightness of the light emitting elements in the viewfinder is varied over a wide range in accordance with the brightness of the image viewed through the viewfinder.